The present invention relates to holding and heat dissipation means for modules of electrical systems. Particularly, the present invention defines an apparatus and method of joining heat-generating modules of a system in order to dissipate heat from the main frame members of such systems. The applicable area of classification is believed to be U.S. Class 361, Sub-class 388.
The design goals of any electro-mechanical system include reliability of performance, serviceability, and efficiency in use of space.
System reliability is dependent upon component failure rate, i.e., the life span of most electrical components is closely related to the temperature at which they operate. In order to hold temperature within acceptable limits, it is often necessary to transfer heat from active heat generating components to passive heat dissipative bodies.
The fundamental problem in transferring heat from one body to another is that of providing a path of thermal conduction between such bodies. This can and has been accomplished by utilizing suitable thermal conducting materials, such as a ductile metal providing, however, that the interface surfaces are designed so that, when pressed together with a predetermined force, the area of metal-to-metal contact will permit a sufficient heat flow or thermal conductivity.
The most common method of achieving proper interface pressures has been through the use of screw fasteners installed with special tools for monitoring of torque. While this procedure has been adequate when applied during initial assembly, under controlled conditions, it has proven unable to insure that a proper torque will be maintained during usage and servicing of the modules. For example, insufficient torque will often result in interfaces developing an unacceptable thermal resistance. Conversely, excessive torque may cause structural failure at a critical surface of the electrical system. Further, an otherwise properly torqued fastener will, over a period of time and due to cyclic thermal expansion and contraction of joint components, eventually loosen, thereby causing an increase, over time, of thermal resistance at a possibly critical interface. A further disadvantage of the prior art approach relates to the manhours which are required in order to perform torque-controlled assembly techniques. Also, package designs must consider space allotment for both screw fasteners and the tools necessary to install them.